The goal of this program is to leverage the clinical and basic research expertise and resources available at Northwestern University to train MD and MD/PhD fellows in infectious disease translational research. This training program will build on the Infectious Diseases Fellowship Program, which attracts top-notch physician-scientists. The clinical expertise of the Infectious Disease Division together with the long-standing basic science strengths in microbiology and immunology at Northwestern University have created a rich environment for translational research. The proposed training program will serve as a nidus of collaboration between these two groups. Each trainee will work with both a primary research mentor and a clinical co-mentor, which will foster interaction between research and clinical faculty and enhance the translational aspects of the fellow's research experience. A training program consisting of a Master's of Science in Clinical Investigation degree, seminars, career development programs, and education in the ethical conduct of research has been developed to promote excellence in research. We propose to fund one highly qualified MD or MD/PhD fellow per year for a two-year intensive research experience. Furthermore, the Northwestern University Department of Medicine has committed to match this award should it be funded, such that resources will be available for a total of two trainees per year to complete two years in the program. Together, these activities will enable trainees to obtain funding and develop into independent researchers.